p53 is a tumor suppressor gene which plays a critical role in cell cycle regulation, and is involved in apoptosis, genomic stability, and inhibition of angiogenesis. For instance, p53 is known to be involved in DNA repair and maintaining growth arrest and ultimately inducing apoptosis if the cell is damaged. In humans, p53 is encoded by the TP53 gene. In some cases the TP53 gene becomes mutated upon exposure to chemicals, radiation, or viruses. These mutations are significant because over 50 percent of human tumors are associated with a mutation or deletion of the TP53 gene.
Lung cancer, in particular, is the leading cause of cancer death worldwide, non-small-cell lung cancer (NSCLC) representing 85% of lung cancer cases. Lung adenocarcinoma, a histologic class of NSCLC, is associated with recurrent mutations in several well-defined oncogenes and tumor suppressor genes. For instance inactivating mutations in the tumor suppressor gene p53 are found in 50% of cases.